This invention relates to a plate structure for use in fluid delivery system for delivering a plurality of fluids, in sequence to a treatment reservoir.
Prior to the present invention, fluid delivery systems have been available which minimize intermixing of fluids while delivering a precise amount of a fluid for chemical reaction. These systems are generally utilized for chemical processes involving a large number of sequentially effected chemical reactions such as in peptide synthesis, DNA synthesis or when sequencing proteins.
U.S. Pat. No. 4,008,736 discloses a valve block containing a capillary formed of capillary segments bored at about 30.degree. from a contact surface of the block. The junctions of the capillary segments are effected at the contact surface and within the block. The junctions at the contact surfaces form valving sites to which are engaged apertured sliding blocks which effect fluid communication with the capillary. While the sliding blocks are effective in providing the desired fluid flow, they wear too rapidly thereby causing undesirable leaks.
U.S. Pat. No. 4,168,724 discloses a similar device but replaces the slider valves with diaphragm valves. The fluid is delivered through the valves from a pressurized fluid storage source. This system requires a vacuum assist to open the valves. This system is undesirable because the type of diaphragm valve used is susceptible to particulate contamination. The pressure drop through the valves is difficult to control which causes less accurate reagent delivery.
U.S. Pat. No. 4,558,845 discloses a fluid delivery system utilize a valve block assembly comprising a separate block for each valve site. The common conduit to the reaction site is alternatively a channel in a block and tubing connecting two adjacent blocks. This arrangement requires a plurality of fittings which are subject to leaking.
U.S. Pat. No. 4,773,446 discloses a valve block assembly which utilizes diaphragm valves. The valves serve to control fluid flow from a plurality of pressurized fluid reservoirs, in sequence to a common outlet reservoir. This system requires the use of conduits from the fluid reservoirs and fittings to valve blocks for each conduit. These fittings are subject to leakage. The fluid delivery systems of the prior art depend upon the use of positive pressure to deliver the fluid and upon the control of back pressure of the fluid reservoir in order to precisely control the amount of fluid delivered to a treatment reservoir. These systems require the frequent adjustment of the fluid delivery means as a function of back pressure. All of the systems set forth above depend upon the precise control of reservoir pressure and restriction through the tubing, channels and valves to control reagent delivery volume. They are very sensitive to variations of the removable reaction columns as regards the delivery volume and flow rate. Also, these systems deliver fluids against back pressures only up to about 10 psig.
Copending U.S. application Ser. No. 07/655,012, filed Feb. 14, 1991, and entitled "Conduit Plate for Fluid Delivery System" discloses a conduit plate for a fluid delivery system comprising four or five layers laminated together, including a plurality of notched openings for attaching external fluid processing components in fluid communication with the plate; and a single fluid conduit layer for effecting passage of fluids between different points on the solid plate. The plate, preferentially is formed of a ceramic material. A plurality of fluids are delivered in sequence to a desired point by means of a plurality of pumps, each comprising a diaphragm member, an injector (a passive outlet check valve), and a passive inlet check valve. The notched openings in the plate address a problem inherent in the manufacture of the solid plate wherein the dimensional tolerances of the solid plate are comparable or larger then the dimension of the passage within the plate so that mating parts can be aligned accurately only insofar as the plate itself serves to key the positions of external components mating to the plate. However, direct attachment of components to the solid plate places the solid plate under tensional forces that may cause breakage. The presence of a single conduit layer in the solid plate results in unique layout of fluid passages in the plate because passages cannot cross each other, an revisions in the fluid path are correspondingly made more difficult. Apparatus which utilize these plates are disclosed in U.S. Pat. Nos. 5,095,932; 5,095,938; 5,111,845 and 5,123,443.
It would be desirable to provide a system which eliminates the need of adjustment of the fluid delivery means. It would also be desirable to utilize a means to deliver accurate fluid volumes which is insensitive to back pressure. Such a system would result in improved system performance and reduced reagent consumption. It would also be desirable to provide a fluid delivery system which minimizes the use of tubes and tube fittings while minimizing the volume of the system as compared to presently available systems. In addition, it would be desirable to provide a fluid delivery plate which can be easily formed, defect free, which does not include easily frangible portions and which can have a reduced size as compared to plates of the prior art.